Neutron Compound Refractive Prisms

The accurate detection of neutrons can make invaluable contributions to the physical, chemical, and biological sciences, and the DoE operates neutron user facilities to support these endeavors. This project will build a compound refractive prism (CRP) that refracts and spatially separates neutrons according to their wavelength, providing greater spatial separation of neutron wavelengths than a single prism or crystal, while countering gravitational effects. Also, the CRP is expected to transmit significantly higher neutron intensities to a sample or detector than a chopper, with less complexity and cost. Two CRP designs will be developed, both using magnetic fields to increase neutron refraction (without decreasing neutron transmission) and providing a means of separating neutrons (based on whether the magnetic spin direction is parallel or antiparallel to the magnetic field direction). The CRP in its simplest form is a row of N prisms which combine to produce an N-fold increased refraction of incident neutrons, compared to a single prism. In the first magnetic CRP design a 0.1-0.3 tesla, V-shaped magnetic field (magnetic prism) will be produced by a pair of small, cube-shaped (3-7 mm) NdFeB magnets with small gaps (1-3mm), fitted in each groove of a non-ferromagnetic CRP. In the second design, the magnetic CRP will be fabricated from ferromagnetic material (Fe, Ni, Co) magnetized parallel to the grooves and ridges. In both designs, neutron refraction will be dependent on neutron wavelength, magnetic field strength, and neutron spin orientation. Commercial Applications and other Benefits as described by the awardee: The proposed device could be applied to materials R&D, non-destructive testing, R&D of magnetic films for information storage, bio-crystallography applied to R&D in proteomics and genomics, and laboratory neutron instrumentation.